ssb: gpio: Add and register software node for GPIO controller

We want to convert the legacy gpio-keys platform device on BCM47XX
boards to use software nodes. To do this properly and allow
referencing the GPIO controller by address rather than relying on
name-based matching (which is being removed from the gpiolib core),
we need to associate the GPIO controller with a software node.

Introduce ssb_gpio_swnode, register it, and associate it with the
gpio_chip.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

2 files changed, 43 insertions, 7 deletions

diff --git a/drivers/ssb/driver_gpio.c b/drivers/ssb/driver_gpio.c
index 905657c925bc..87922479946c 100644
--- a/drivers/ssb/driver_gpio.c
+++ b/drivers/ssb/driver_gpio.c
@@ -15,8 +15,14 @@
 #include <linux/interrupt.h>
 #include <linux/irqdomain.h>
 #include <linux/export.h>
+#include <linux/property.h>
 #include <linux/ssb/ssb.h>
 
+const struct software_node ssb_gpio_swnode = {
+	.name = "ssb-gpio",
+};
+EXPORT_SYMBOL_GPL(ssb_gpio_swnode);
+
 
 /**************************************************
  * Shared
@@ -232,6 +238,8 @@ static int ssb_gpio_chipco_init(struct ssb_bus *bus)
 	chip->to_irq		= ssb_gpio_to_irq;
 #endif
 	chip->ngpio		= 16;
+	if (bus->bustype == SSB_BUSTYPE_SSB)
+		chip->fwnode	= software_node_fwnode(&ssb_gpio_swnode);
 	/* There is just one SoC in one device and its GPIO addresses should be
 	 * deterministic to address them more easily. The other buses could get
 	 * a random base number.
@@ -433,10 +441,12 @@ static int ssb_gpio_extif_init(struct ssb_bus *bus)
 	 * deterministic to address them more easily. The other buses could get
 	 * a random base number.
 	 */
-	if (bus->bustype == SSB_BUSTYPE_SSB)
-		chip->base		= 0;
-	else
-		chip->base		= -1;
+	if (bus->bustype == SSB_BUSTYPE_SSB) {
+		chip->base	= 0;
+		chip->fwnode	= software_node_fwnode(&ssb_gpio_swnode);
+	} else {
+		chip->base	= -1;
+	}
 
 	err = ssb_gpio_irq_extif_domain_init(bus);
 	if (err)
@@ -464,11 +474,33 @@ static int ssb_gpio_extif_init(struct ssb_bus *bus)
 
 int ssb_gpio_init(struct ssb_bus *bus)
 {
+	int err = 0;
+
+	/*
+	 * Register software node only for the host SoC bus. There is only
+	 * one SoC instance in the system, so there are no concerns with
+	 * registration conflicts.
+	 */
+	if (bus->bustype == SSB_BUSTYPE_SSB) {
+		err = software_node_register(&ssb_gpio_swnode);
+		if (err)
+			return err;
+	}
+
 	if (ssb_chipco_available(&bus->chipco))
-		return ssb_gpio_chipco_init(bus);
+		err = ssb_gpio_chipco_init(bus);
 	else if (ssb_extif_available(&bus->extif))
-		return ssb_gpio_extif_init(bus);
-	return -1;
+		err = ssb_gpio_extif_init(bus);
+	else
+		err = -ENODEV;
+
+	if (err) {
+		if (bus->bustype == SSB_BUSTYPE_SSB)
+			software_node_unregister(&ssb_gpio_swnode);
+		return err;
+	}
+
+	return 0;
 }
 
 int ssb_gpio_unregister(struct ssb_bus *bus)
@@ -476,6 +508,8 @@ int ssb_gpio_unregister(struct ssb_bus *bus)
 	if (ssb_chipco_available(&bus->chipco) ||
 	    ssb_extif_available(&bus->extif)) {
 		gpiochip_remove(&bus->gpio);
+		if (bus->bustype == SSB_BUSTYPE_SSB)
+			software_node_unregister(&ssb_gpio_swnode);
 		return 0;
 	}
 	return -1;
diff --git a/include/linux/ssb/ssb.h b/include/linux/ssb/ssb.h
index 7fee9afa9458..67cb66f6f5ed 100644
--- a/include/linux/ssb/ssb.h
+++ b/include/linux/ssb/ssb.h
@@ -671,4 +671,6 @@ int ssb_pcibios_plat_dev_init(struct pci_dev *dev);
 int ssb_pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin);
 #endif /* CONFIG_SSB_EMBEDDED */
 
+extern const struct software_node ssb_gpio_swnode;
+
 #endif /* LINUX_SSB_H_ */